Ms. Kidwell plays Teacher Caroline, who in the game is the general of the Union Army. Mr. Sheppard plays Teacher Stuart, her Confederate counterpart. Like their characters, Ms. Kidwell and Mr. Sheppard are a study in contrasts, not just physically — she’s more compact, he’s lankier; she’s black, he’s white — but also in personality, background, outlook.

Her humor is dry and jabbing, her conversation inquisitive and disputatious. A chatty Baltimore native, she can shift easily between academic-speak (at Columbia, she studied the literature of marginalized communities) and astrology. She’s been in the thick of debates over racial politics, having played the fictional black artist Donelle Woolford in Joe Scanlan’s “Dick’s Last Stand,” a piece that drew heat from some actual black artists at the 2014 Whitney Biennial.